1. Field of the Invention
The present invention relates to a ball grid array semiconductor package, and more particularly, to a ball grid array semiconductor package having a heat ring and a heat slug both coated with a metal medium layer and an insulation layer for providing improved heat dissipation efficiency, overall electrical performance and enhanced bonding capability.
2. Description of Related Art
With the rapid advances in the field of electronic engineering, the function of a semiconductor device is getting more and more complicated, and the number of pins of the semiconductor device is increased rapidly. Therefore, the ball grid array (BGA) package, which allows more pins to be arranged in a semiconductor device, is welcomed and widely used. However, the semiconductor device with complicated function is usually provided with a high signal processing speed so that the semiconductor device may generate excess heat when working. Therefore, it is important to dissipate the excess heat away thereby maintaining the semiconductor device to operate in a proper range of temperature.
U.S. Pat. No. 5,708,567 granted to Shim et al. has provided an BGA semiconductor package with ring-type heat sink to improve the heat dissipation efficiency. With reference to FIG. 10, the ring-type heat sink (71) is attached to a substrate (72) via an extended portion of a die paddle (75) such that the heat sink (71) surrounds the encapsulant (74) of the package. Therefore, heat generated by the die (73) can be dissipated via the extended die paddle (75) and the heat sink (71). Furthermore, because the heat sink (71) surrounds the die (73), it also contributes in providing electrical shielding effect. However, for such a semiconductor package, heat cannot be effectively dissipated via the encapsulant (74). The bonding wires (76), that are used to electrically connect the die (73) with the substrate (72), are not shield by metal. Moreover, the adhesive bonding between the encapsulant (74) and the extended die paddle (75) is not satisfactory. Accordingly, the reliability of such a semiconductor package is low.
U.S. Pat. No. 5,736,785 granted to Chiang et al. has provided a semiconductor package with a heat spreader to improve the heat dissipation efficiency. With reference to FIG. 11, the semiconductor package has a heat spreader (81) attached over a die (83) which is mounted on a substrate (82). The heat spreader (81) contacts with the die (83) so that heat generated by the die (83) can be transferred to the heat spreader (81). The die (83) and the heat spreader (81) are covered by a packaged body (87). Encapsulation material, such as epoxy, is filled in the packaged body (87). With this package structure, heat generated by the die (83) can be dissipated away via the heat spreader (81). Furthermore, because the heat spreader (81) is attached over the die (83), part of the bonding wires (86) can be shielded by the heat spreader (81). However, because the path to dissipate heat for such a package structure is restricted in the upper surface area thereof, the heat dissipation efficiency is limited. The electrical shielding is only provided on an area above the die (83) and bonding wires (86). The conductive trace (not shown) on the outer area of the substrate (82) is not shielded. Moreover, the bonding effect between the epoxy encapsulant (84) and the heat spreader (81) is not satisfactory so that the reliability of the packaged semiconductor device is low. Therefore, there is a need for the above semiconductor package to be improved.